1. Field of the Invention
This invention relates to novel surfactants for emulsion polymerization for control of latex particle size and stability.
2. Description of Prior Art
While surfactants are widely used in emulsion polymerizations, for most subsequent applications in coatings, adhesives, binders and the like, their presence is detrimental. They may contribute negatively to water resistance, adhesion, corrosion resistance, and block resistance of the film, and frequently also increase the tendency to foam, and affect the capability and stability of the latex in its formulations.
The use of ultrafine latexes has been an important advantage in latex coating technology and often can impart the important properties of chalk adhesion, better film formation and water resistance. The conventional method of making such ultrafine latexes, however, requires large amounts of surfactant because of the large latex particle surface area. Therefore, the improvement due to ultrafine latexes can be transitory and lost on aging formulation, heating, or a combination of these. Presumably, the surfactant equilibrates with the surfaces of all the materials in the formulation.
Various polymerizable surfactants have been described in the literature and are available commercially. One such series of surfactant is described in U.S. Pat. No. 4,049,608 to Steckler et al. However, the Steckler et al surfactants suffer from the disadvantage of only having two allylic protons per molecule. Some other commercial surfactants have relatively reactive graft sites, such as allylesters and maleates. The problem with most of the prior polymerizable surfactants is that virtually all of them have the reactive group in the wrong end of the soap molecule.